1. Field of the Invention
The present invention relates to an apparatus and a method for controlling a motor. More particularly, the present invention relates to an apparatus and a method for controlling a motor driving a continuously variable valve lift device.
2. Description of Related Art
A continuously variable valve lift (hereinafter, referred to as ‘CVVL’) system varies an opening/closing level of a valve by varying a press level of a cam through rotation of an eccentric control shaft. In this case, a valve lift representing the opening/closing level of the valve is determined according to an angle value of the control shaft and the angle value of the control shaft is varied by a motor.
The CVVL system varies the angle value of the control shaft within a predetermined operation range by controlling the motor according to a difference between a present value and a target value of the valve lift so as to control the valve lift. In this case, in the CVVL system, since the valve lift determines an air volume, i.e., a driving force of an engine, control performance of the valve lift is a key element to determine control and reaction performance of the engine.
When an apparatus is controlled through the motor, the motor consumes high current due to conditions (e.g., cold starting, before breaking in a vehicle, high RPM, and the like) in which control resistance of the apparatus is deteriorated.
In this case, when an internal temperature of the apparatus is increased by the high current, an electrical endurance limit and rigidity of each component are deteriorated and a current-resistant value of a wire on which the high current flows is decreased with an increase in a surrounding temperature, such that the wire may be damaged or a fire may occur.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.